This invention relates to an information processing system, and more particularly to a system including an information processing apparatus having a plurality of slots, e.g. connectors or sockets onto which respective ones of a plurality of types of adapters can be mounted.
Information processing systems such as computer terminals or the like, are provided with a number of adapters, which support general purpose interfaces in order to meet a variety of user's requests. Usually each type of the adapters has a unique address area allocated thereto by the system. Also, upon user's requests any one of the adapters is mountable on any desired one of the slots.
In such a system allowing any type of the adapter to be mounted on any slot, it is necessary to set control data for controlling priority of interrupt requests, direct memory access, or the like depending on the system configuration i.e. the types and combination of the mounted adapters. One approach to this requirement is taught in Japanese laid-open patent No. 61-220054. In this disclosure a unique number is physically assigned to each of the slots and a unique address area is allocated to each of the types of adapters. In determining the system configuration addresses of all types of adapters are sequentially accessed by a processor. If the adapter accessed by the processor is mounted on any one of the slots, the adapter will return the number assigned to the slot to the processor. Thus, the processor knows what type of adapter is actually mounted on which slot thereby automatically setting the priority control data or the like.
A high-speed, high-performance and multi-functional computer terminal, such as an engineering workstation, which has appeared in recent years, allows many types of external devices to be connected thereto. The external devices include printers, external hard disc drives, external floppy disc drives, modems, card readers, light pens, etc. These external devices are connected to the workstation typically via general purpose interfaces such as RS-232C, GPIB, SCSI or the like.
In order to connect to a large number of such external devices, the workstation requires a number of adapters mountable thereon which support the general purpose interfaces.
It is, however, difficult to mount two or more of the same type of adapters at the same time since the prior art approach assigns a unique address area to each type of the adapters to determine the system configuration. Although this may be overcome by giving different addresses to the same type of adapters, it will result in a virtual increase of the types of adapters, leading to a running short of the address space available to allocate to the adapters. Also, it becomes complex to manage the adapters because of the various combinations thereof.
Moreover, the prior art approach to determine the system configuration requires a number of times of accessing addresses since the accesses are sequentially done to the addresses allocated to all types of adapters to determine the identity of the mounted adapters.